Transient Ischemic Attack (TIA) or mini-stroke is an episode of acute focal neurological symptoms that lasts less than 24 hours. TIA is an important precursor of stroke - about 5% of TIA cases develop strokes within 48 hours, and a further 5% suffer this potentially devastating event over the next 90 days. The management of the approximately 300,000 TIA cases treated in U.S. emergency departments (EDs) every year represents a major clinical dilemma in that there is no standard for determining the disposition of TIA cases (i.e., which cases should be hospitalized and which should be managed on an out-patient basis). Clinical practice is therefore highly variable - some EDs hospitalize the majority of cases while others hospitalize relatively few. The management of TIA therefore represents a classic problem from the perspective of health care quality and resource allocation. The ABCD2 rule is a validated clinical decision rule (CDR) developed to risk stratify TIA cases in the ED. The rule stratifies TIA cases into 3 groups (i.e., low, moderate, high) based on their short-term risk of stroke. We propose to develop a more rational clinical approach to the management of TIA which targets care to the most at-risk cases while avoiding the expense and hazard of hospitalizing low risk cases. In this application, we will: 1) Develop a cost-effectiveness analysis (CEA) model that compares the costs and benefits of hospital versus out-patient care for TIA cases presenting to the ED, and determine the influence of risk stratification (as measured by the ABCD2 rule) on the results of this model;2) Assess the acceptability, feasibility, and barriers to using the ABCD2 rule by conducting focus groups with emergency medicine (EM) physicians, as well as a survey of 400 members of the Michigan College of Emergency Physicians;and 3) Through the development of case vignettes, study how clinical decisions of EM physicians are influenced by data from the CEA model, and how this impacts their management of TIA cases in the ED. Developing a rational and cost-effective approach to TIA management in the ED is a major public health priority. Understanding the relative costs and benefits of hospitalization for different TIA risk-groups provides critical data for developing a more rational disposition strategy. The ABCD2 rule has great potential to improve the clinical management of TIA patients in a more cost-effective manner. This project collects data needed to achieve our ultimate objective of conducting an implementation study of the ABCD2 rule in community-based EDs. This application also addresses several AHRQ priorities including translational research and the efficiency and appropriateness of medical care. This application is also relevant to vulnerable inner city populations who use the ED as their primary source of care.